i66 



BIOLOGICAL PHYSICS 



that of the motor nerves, and it must necessarily follow 



that the substances circulated have to find a means of 



distal outlet, as backward progress, at least of the two 



inner, is safeguarded, by appropriate means elsewhere 

 described. 



// 



FIG. 62. SECTION OF EPIDERMIS FROM THE HUMAN HAND. Highly 

 magnified. (Ranvier. ) 



U, horny layer, consisting of s, superficial horny scales : sw, swollen-out horny cells ; 

 s.l, stratum lucidum ; M, rete mucosum or Malpighian layer, consisting of 

 /, prickle-cells, several rows deep ; and c, elongated cells forming a single stratum 

 near the corium. 1 he granular cells of Langerhans, which lie just below the 

 stratum lucidum. are not shown, n, part of a plexus of nerve-fibres in the 

 superficial layer of the cutis vera. From this plexus, fine varicose nerve-fibrils 

 may be traced passing up between the cells of the Malpighian layer. 



Where then are we to look for the means of their 

 final disposal when they have become effete, and no 

 longer capable of retention within the body, without 

 the danger of pathogenesis ? The disposal of the neural 

 lymph, or the fluid, circulated by the two outer tubes 

 has been traced in some detail to the sweat glands (Fig. 

 15), and to excretion through the skin, and into the 

 sarcolemmar sheaths of the muscle fibres. Where then 



